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Biomedical subjects

H Christensen

Publications and source records attributed to H Christensen.

At least 199 records · Page 11Linked to original sources
PubMed1994

Diverting colostomy induces mucosal and muscular atrophy in rat distal colon.

The progress of adaptive changes in the left colon after diverting colostomy was studied in rats using stereological techniques. Standardised segments of left colon proximal and distal to the colostomy was examined after 0, 1, 2, 4, or 12 weeks. In excluded colon the mucosal weight was reduced by 37% (p < 0.01) and the luminal surface area by 47% (p < 0.01) after four weeks and reached a steady state at this point of time, as no further reduction was seen from 4 to 12 weeks. The number of proliferating crypt cells was determined immunohistochemically after in vivo labelling with bromodeoxyuridine and was compared with the total number of colonocytes. Total bowel rest leads to a reduction in the number of proliferating epithelial cells and not to a reduced average life span. The weight of the muscularis propria decreased by 32% after four weeks (p < 0.01) and by 48% after 12 weeks (p < 0.001), whereas the weight of the submucosa was unchanged. No adaptive changes were found in segments proximal to the colostomy. These results show that the wall composition of defunctioned colon in rats is radically changed resulting from a mucosal and muscular atrophy, and from a reduction in luminal surface area.

Animals↗
PubMed1994

Growth hormone treatment of rats with chronic diverting colostomy. Differential response on proximal functioning and distal atrophic colon.

Diversion of colon from the fecal stream leads to profound intestinal atrophy. After diverting colostomy for 4 weeks, female rats were treated with biosynthetic human growth hormone (b-hGH; 2.0 mg.kg-1 body wt.day-1) in order to investigate whether b-hGH could reverse atrophic changes in distal colon, with special reference to changes in morphometric composition, collagen content and biomechanical properties. Biosynthetic hGH treatment for 28 days stimulated growth of the muscularis propria of the defunctioned, atrophic colon (p < 0.05), whereas the mucosal atrophy was unaffected by the treatment. In colon proximal to the colostomy, however, b-hGH increased the colonic wet weight (p < 0.01), defatted dry weight (p < 0.005) and the collagen content (p < 0.05). Morphometric analysis showed that the growth increase was localized to the mucosa and the muscularis propria. In conclusion, fecal diversion alters the response of b-hGH treatment and indicates that the trophic effect of growth hormone on colonic mucosa is dependent on fecal bulk passage, whereas the trophic effect on muscularis propria is fully retained when colon is deprived of luminal nutrients.

Animals↗
PubMed1994

Growth hormone increases the collagen deposition rate and breaking strength of left colonic anastomoses in rats.

BACKGROUND: The purpose was to investigate how growth hormone exerts its stimulating effect on the healing of experimental colonic anastomoses. METHODS: Rats were treated with biosynthetic growth hormone (bGH); the anastomotic breaking strength, collagen content, and collagen deposition rate (labeling of collagen with 14C-proline) were compared to saline treated controls. RESULTS: bGH increased the breaking strength when the rats were treated before and after the operation and when bGH treatment was started at operation and continued during the healing period. No effect on these parameters was seen, however, when treatment was given only before operation. The collagen deposition rate of the intact colon was accelerated from 0.6% to 1.0% per hour at operation after 7 days of preoperative treatment. The anastomotic collagen deposition rate was increased on day 4 from 4.4% in the controls to 9.0% in the anastomosed rats given bGH from operation and to 12.9% in rats given bGH from 7 days before operation until day 4 after operation, resulting in a higher anastomotic collagen content. CONCLUSIONS: Treatment of rats with bGH in the healing phase increases the breaking strength of colonic anastomoses caused by a stimulation of the collagen deposition rate of the anastomotic segment.

Anastomosis, Surgical↗
PubMed1993

Kinetics of folding of the all-beta sheet protein interleukin-1 beta.

The folding of the all-beta sheet protein, interleukin-1 beta, was studied with nuclear magnetic resonance (NMR) spectroscopy, circular dichroism, and fluorescence. Ninety percent of the beta structure present in the native protein, as monitored by far-ultraviolet circular dichroism, was attained within 25 milliseconds, correlating with the first kinetic phase determined by tryptophan and 1-anilinonaphthalene-8-sulfonate fluorescence. In contrast, formation of stable native secondary structure, as measured by quenched-flow deuterium-hydrogen exchange experiments, began after only 1 second. Results from the NMR experiments indicated the formation of at least two intermediates with half-lives of 0.7 to 1.5 and 15 to 25 seconds. The final stabilization of the secondary structure, however, occurs on a time scale much greater than 25 seconds. These results differ from previous results on mixed alpha helix-beta sheet proteins in which both the alpha helices and beta sheets were stabilized very rapidly (less than 10 to 20 milliseconds).

Circular Dichroism↗
PubMed1993

The disabled elderly living in the community: care received from family and formal services.

OBJECTIVES: Based on a community sample, to assess the reasons disabled elderly people need care, the type of formal services they receive, the characteristics of their carers and the degree of psychological morbidity in these carers. DESIGN AND SETTING: A community survey of people aged 70 or more years living in Canberra or Queanbeyan. Survey participants were asked to nominate informants, who were interviewed about the subjects' state of health. The informants provided information on need for care, services received and the role of carers. Informants also reported on their own health, including symptoms of anxiety and depression. RESULTS: Elderly people needed care because of physical disability more often than behavioural disability. Those with physical disability received more formal services and more help from health professionals than those with behavioural disability. Contact with general practitioners was high for both disabled and non-disabled subjects. Carers of the physically disabled had raised levels of anxiety and symptoms of depression, and poorer self-rated health, but carers of the behaviourally disabled did not. Wives, daughters and husbands made up the biggest categories of carers and around two-thirds of carers were women. CONCLUSION: Family carers play an important role in maintaining disabled elderly people in the community and this role is often stressful. Formal services have to be aimed as much at the needs of the carers as at the disabled people themselves.

Activities of Daily Living↗
PubMed1993

Decrease in collagenous proteins and mechanical strength of distal colon after diverting colostomy in rats.

The effects of a diverting colostomy on weight, collagen content, and biomechanical strength of the left colon was investigated in rats. Female rats received either a diverting colostomy or a sham-operation and were killed randomly 1, 2, 4, or 12 weeks after surgery. The dry weight and hydroxyproline content of excluded colon decreased by 37% (P < 0.001, confidence limits (CL) = 21-53%) and 25% (P < 0.001, CL = 18-31%), respectively, after 4 weeks, and by 52% (P < 0.001, CL = 38-66%) and 40% (P < 0.001, CL = 27-53%), respectively, after 12 weeks compared to sham-operated rats. The breaking strength of the defunctioned colon decreased by 21% (P < 0.05, CL = 2-40%) after 4 weeks and by 25% after 12 weeks (P < 0.05, CL = 4-46%). The tensile strength of defunctioned colon (load per unit collagen) was reduced by 19% after 4 weeks (P < 0.05, CL = 6-32%). Proximal to the colostomy site we found no differences in the hydroxyproline content or biomechanical strength. In conclusion, defunctioning of the left colon in rats leads to deterioration in the biomechanical properties caused by a lesser content and a decreased quality in the collagen of the left colon.

Animals↗
PubMed1993

Quantitative EMG findings at different force levels in patients with myasthenia gravis.

Quantitative electromyography, comprising manual motor unit potential analysis at weak effort and turns/amplitude analysis at 30% of maximum force were performed in the brachial biceps muscle of 17 patients with myasthenia gravis (MG). Findings simulating myopathic and less often neurogenic changes were observed in seven out of 17 patients, suggesting that the myasthenic muscle may have random block of muscle fibres, functional block of the main part or whole motor units or a changed recruitment pattern. In addition, turns/amplitude analysis was performed at low force levels (10% of maximum force) both before and after a provocative manoeuvre consisting of a maximum effort sustained for 1 min, and at maximum force at the beginning and at the end of the provocation itself. Turns/amplitude analysis at low force failed to differentiate MG patients from controls. The relative change of ratio of turns to mean amplitude calculated from 10% to maximum force (at the beginning of the provocative manoeuvre) was increased in seven out of eight patients compared to the controls. This last finding seems to be useful in differentiating MG patients from patients with myopathy.

Adolescent↗
PubMed1993

The prevalence of depressive disorders and the distribution of depressive symptoms in later life: a survey using Draft ICD-10 and DSM-III-R.

The point prevalence of depressive disorders was estimated in a sample of persons aged 70 years and over, which included both those living in the community and those in institutional settings. Lay interviewers administered the Canberra Interview for the Elderly to the subjects and their informants. The point prevalence of depressive episodes as defined by the Draft ICD-10 diagnostic criteria was 3.3%. The rate for DSM-III-R major depressive disorder was 1.0%. The latter prevalence rate is similar to those reported elsewhere for the elderly. Evidence is accumulating that older persons may indeed have low rates for depressive disorders at the formal case level. Possible reasons for this finding are offered. A scale for depressive symptoms, based exclusively on those specified in Draft ICD-10 and DSM-III-R, showed that the elderly do experience many depressive symptoms. Contrary to expectation, these did not increase with age. The number of depressive symptoms was correlated with neuroticism, poor physical health, disability and a history of previous depression. Attention now needs to be directed to the clinical significance of depressive symptoms below the case level in elderly persons.

Age of Onset↗
PubMed1993

The association between mental, social and physical activity and cognitive performance in young and old subjects.

The influence of mental, social and physical activity on fluid, crystallized and memory tasks was examined in 60 young and 56 elderly subjects using multiple regression. Once the influence of education, age, health and psychiatric morbidity was removed, physical activity was associated with higher fluid test performance in old but not in young subjects. Moreover, mental activity was associated with higher performance on fluid and crystallized tasks for subjects with low education but not for subjects with high education.

Aged↗
PubMed1993

The Canberra Interview for the Elderly: assessment of its validity in the diagnosis of dementia and depression.

The Canberra Interview for the Elderly (CIE) has been developed as a field instrument for identifying cases of dementia and depression, according to the diagnostic criteria in both draft ICD-10 and DSM-III-R. It has been designed to be administered by lay interviewers and responses are assembled algorithmically to derive diagnoses. The validity of the CIE was assessed using a sample of 75 elderly patients attending a hospital clinic. The CIE diagnoses were compared with clinical judgements made at the time of recruitment into the study and later by 3 clinicians using the information collected by the lay interviewers. Agreement between the CIE and the clinicians' diagnoses was as great as agreement between the clinicians themselves, meeting or exceeding agreement observed for comparable instruments designed for lay administration.

Aged↗
PubMed1993

Effect of growth hormone on the inflammatory activity of experimental colitis in rats.

The effect of daily treatment with 2.0 mg biosynthetic human growth hormone per kilogram body weight or isotonic NaCl (controls) on experimental colitis was investigated in rats. Colonic inflammation was induced by instillation of trinitrobenzene sulfonic acid (TNB) intraluminally into the left colon. Untreated NaCl-instilled rats were used for comparison with intact colon. Four days after TNB instillation the growth hormone-treated rats had lower macroscopic and microscopic damage scores and less infiltration of neutrophils, measured as myeloperoxidase activity (MPO), than controls. The biomechanical properties of the colon showed that the breaking strength and energy absorption were reduced in the control rats with colitis compared with intact colon, whereas the rats treated with growth hormone had unchanged strength and energy absorption. The differences in MPO activity, damage scores, and biomechanical properties were associated with a higher concentration of insulin-like growth factor I in serum from growth hormone-treated rats after 4 days than controls. Finally, the growth hormone-treated rats regained their initial body weight after 7 days, in contrast to the body weight of control rats, which remained 11% lower than their initial body weight.

Animals↗
PubMed1992

[Hepatocellular adenoma after oral contraception].

Raised serum basic phosphatase was found incidentally in a woman aged 43 years. Investigation with biopsy revealed a hepatocellular adenoma. The tumour regressed after withdrawal of Neogentrol oral contraception which the patient had consumed for 17 years. The patient did not desire invasive treatment. Employment of oral contraceptive steroids for more than two years is associated with increased occurrence of hepatocellular adenomata. The hepatocellular adenoma is a clearly delimited, most frequently solitary, benign tumour with limited malignant potential but with a considerable risk of rupture with haemorrhage even after withdrawal of oral contraception. The hepatocellular adenoma has no malignant tumour vessels (in contrast to hepatocellular carcinoma) and it appears as a cold region on scintigraphy (in contrast to focal nodular hyperplasia), but the diagnosis can only be established with certainty by histological examination. The hepatocellular adenoma consists most frequently of large pale hepatocytes in trabeculae surrounded by a net of reticulin and separated by sinusoids. Biliary passage and portal spaces do not occur. The best treatment consists of excision of the tumour or embolisation. If invasive treatment is postponed, regular scanning should be performed to observe regression or progression of the tumour and oral contraception and pregnancy should be advised against on account of the risk of growth of the tumour.

Adult↗
PubMed1992

[Elimination of human chorionic gonadotropin in serum and urine after uncomplicated induced abortion during the first trimester].

Serum chorion gonadotropin was measured weekly in 12 women from the time of legal first trimester abortion until values were below 10 IU/L. The elimination followed a 2-component curve. The half-life in the first few days was 1.1 day, hereafter 4.2 days. Serum-HCG decreased to less than 10 IU/L within 22 to 40 days. The elimination of serum-HCG was found to decrease so uniformly, that values which do not decrease must be considered abnormal. A sensitive bedside urine-HCG test was found to be positive from 13 to 31 days after the abortion.

Abortion, Induced↗
PubMed1992

Age-related alterations in the strength and collagen content of left colon in rats.

The biomechanical properties and intestinal wall composition of left colon were studied in 4-month-old, 14-month-old, and 27-month-old male rats. The hydroxyproline content and hydroxyproline concentration in old rats were increased by 36% and 26%, respectively, compared with young rats and by 20% and 17%, respectively, compared with middle-aged rats. In middle-aged rats the maximum load increased by 21%, compared with young rats. In old rats, however, the maximum load decreased by 13%, compared with middle-aged rats. Histological examination showed that the mean crypt height was 9% higher in middle-aged rats and 12% higher in old rats than in young rats. In conclusion, an accumulation of collagenous proteins was found in old rats compared with middle-aged rats and this was accompanied by a decrease in the strength, which may deteriorate the functional integrity of the left colonic wall with age.

Aging↗
PubMed1992

The ontogeny of the uptake systems for glutamate, GABA, and glycine in synaptic vesicles isolated from rat brain.

The ontogeny of the uptake of glutamate, GABA and glycine into synaptic vesicles isolated from rat brain has been investigated. The vesicular uptake of the three amino acids increased with developmental age in parallel with synaptogenesis, indicating a functional role of uptake of the amino acids by synaptic vesicles in the nerve terminals. Uptake of the amino acids by plasma membrane particles (synaptosomes) in brain homogenate showed a somewhat different developmental profile. The uptake of glutamate increased markedly with developmental time, while the uptake of GABA showed only a slight increase. Uptake of glycine by plasma membrane particles was very low and therefore not registered. The observed developmental increase in uptake of glycine by synaptic vesicles isolated from brain, supports previous reports indicating that glycine can be taken up by vesicles from non-glycine terminals.

Adenosine Triphosphate↗
PubMed1992

Cholinergic 'blockade' as a model of the cognitive deficits in Alzheimer's disease.

The performance of 44 Alzheimer patients and 33 controls was examined on tests previously found to be differentially affected by scopolamine administration. Tests of secondary memory, performance intelligence, primary memory, semantic retrieval, procedural memory and verbal intelligence were included. It was found that Alzheimer patients performed more poorly than controls on tests of secondary memory, as measured by selective reminding, recall and recognition. Procedural memory, as measured by stem completion, homophone spelling and transformed text reading, did not differ between Alzheimer patients and controls. Semantic memory, verbal intelligence and primary memory were impaired in moderate and severe cases. However, patients with 'mild' dementia, as measured by the Mini-Mental State Examination, did not differ from controls on tests of semantic memory, verbal intelligence and primary memory. It was concluded that the pattern of anterograde memory deficits and preserved abilities in mild dementia mimicked that previously observed in scopolamine administration in young subjects.

Aged↗
PubMed1992

Nocturnal variations in human lower leg subcutaneous blood flow related to sleep stages.

Nocturnal subcutaneous adipose tissue blood flow rate was measured in the lower legs of 10 normal human subjects together with systemic arterial blood pressure, heart rate, and registration of sleep stages under ambulatory conditions. The 133Xe washout technique, portable CdTe(Cl) detectors, and a portable data storage unit were used for measurement of blood flow rates. The sleep recordings were performed with a portable computerized sleep analysis system. In accordance with the results of previous studies, a hyperemic blood flow rate phase (mean increase 140%) for 100 min was observed approximately 60 min after the subjects went to bed. The moment of onset of the hyperemic phase was closely related to the moment of onset of the first episode of deep sleep (stages 3 and 4). There was a significant (P < 0.01) overrepresentation of deep sleep in the hyperemic phase compared with adjacent phases, and rapid-eye-movement sleep predominantly occurred in the latter part of the night, when the subcutaneous blood flow rate was stable. The results of the present study are in accordance with current theories of the interrelationship between the thermoregulatory and the arousal state control systems and, thus, might suggest that the nightly subcutaneous hyperemia represents a thermoregulatory effector mechanism.

Adipose Tissue↗